docs: def session_check_name(session_name):
      """
      Raises exception session name invalid, modeled after tmux function.
  
      tmux(1) session names may not be empty, or include periods or colons.
      These delimiters are reserved for noting session, window and pane.
  
      Parameters
      ----------
      session_name : str
          Name of session.
  
      Raises
      ------
      :exc:`exc.BadSessionName`
          Invalid session name.
      """
      if not session_name or len(session_name) == 0:
          raise exc.BadSessionName("tmux session names may not be empty.")
      elif '.' in session_name:
          raise exc.BadSessionName(
              "tmux session name \"%s\" may not contain periods.", session_name
          )
      elif ':' in session_name:
          raise exc.BadSessionName(
              "tmux session name \"%s\" may not contain colons.", session_name
          )